Not just more common, it's somewhat taboo the other way around.
One of my brothers in his mid 20s briefly dated some girl a bit older than him, maybe late 20s/early 30s.
When my parents found out, he got chastised for it (in a somewhat playful way albeit). They did not necessarily like this, the kicker is they have an 11 year age gap themselves, but it's my father who's older.
